[Retros] Two little SPG-challenges

[Mario Richter]

Dear retro-friends,

maybe I can use the current low traffic on this
mailing-list to present to you two little challenges.

While playing a little bit with the "At-Home-Proofgame"-
theme, I found the following to positions:

Position A:


+---+---+---+---+---+---+---+---+

|*R |*S |*B | . |*K |*B |*S |*R |

+---+---+---+---+---+---+---+---+

|*P |*P | . |*P |*P |*P |*P |*P |

+---+---+---+---+---+---+---+---+

|   | . |   | . |   | . |   | . |

+---+---+---+---+---+---+---+---+

| . |   | . |   | . |   | . |   |

+---+---+---+---+---+---+---+---+

|   | . |   | . |   | . |   | . |

+---+---+---+---+---+---+---+---+

| . |   | . |   | . |   | . |   |

+---+---+---+---+---+---+---+---+

| P | P | P | P |   | P | P | P |

+---+---+---+---+---+---+---+---+

| R | S | . |   | K | B | S | R | (13 + 14)

+---+---+---+---+---+---+---+---+

rnb1kbnr/pp1ppppp/8/8/8/8/PPPP1PPP/RN2KBNR

SPG in 7.5 moves


Position B:

+---+---+---+---+---+---+---+---+

|*R |*S |*B |*Q |*K | . |*S |*R |

+---+---+---+---+---+---+---+---+

|*P |*P |*P |*P |*P |*P | . |   |

+---+---+---+---+---+---+---+---+

|   | . |   | . |   | . |   | . |

+---+---+---+---+---+---+---+---+

| . |   | . |   | . |   | . |   |

+---+---+---+---+---+---+---+---+

|   | . |   | . |   | . |   | . |

+---+---+---+---+---+---+---+---+

| . |   | . |   | . |   | . |   |

+---+---+---+---+---+---+---+---+

| P | P | P | P | P | P | P | . |

+---+---+---+---+---+---+---+---+

| R |   | B | Q | K | B | . |   | (12 + 13)

+---+---+---+---+---+---+---+---+

rnbqk1nr/pppppp2/8/8/8/8/PPPPPPP1/R1BQKB2

SPG in 7.0 moves

(If these problems are already published or
 otherwise anticipated, I would be grateful,
 if somebody could provide author and source.)


First challenge:

Can you do better than 'natch' on a 350MHz-PII-machine?

(natch - with 128MB hash-table - solves 
 - Pos A in  3min 50s
 - Pos B in 34min 04s)


If some of you try to solve the two problems,
I would be grateful if you can send me your 
solving times.


Second challenge:

Both proof games contain a rather paradoxical
element (at least I consider them that way).

Can you construct longer proof games (not
necessarily of the "At-Home"-type), which show
the same element?


   greetings
     mario